Recently, due to the development of various social networks such as cloud computing and social networking, the content of information using communication line has been dramatically increased. For the purpose of coping with such a rapid increase of the information content, techniques to attain the increase of the bandwidth of information communication have been sought. The wavelength division multiplexing (WDM) communication using silicon photonics technique is one of such attempts, and is expected to be capable of attaining broadband communication on the basis of compact and inexpensive circuits as compared with the conventional silica-based wavelength division multiplexing communication.
In WDM scheme, lights of a plurality of proximal wavelengths are multiplexed and are simultaneously transmitted, and accordingly, there is required a function of multiplexing the light signals of a plurality of wavelengths, and extracting optical signals of optional wavelengths from the multiplexed light signals. A device actualizing such a function is an optical waveguide circuit mounting a multi/demultiplexer and the like.
In an optical waveguide circuit using silicon photonics technique, a multi/demultiplexer such as an AWG uses silicon as a waveguiding medium. However, in a silicon waveguide, the variation of the light refractive index is possibly caused due to a slight deviation in the waveguide width caused during fabrication or the temperature of the use environment. Accordingly, when a silicon waveguide is used for an optical waveguide circuit for the wavelength division multiplexing communication or the like, there has been required a compensation based on the modulation of the temperature of the device.
The regulation based on the thermal compensation of the optical waveguide for the wavelength division multiplexing communication is generally applied to WDM devices using silica waveguides. For example, JP2002-90558A discloses an optical waveguide element module for wavelength division multiplexing communication using a silica-based waveguide. The optical waveguide element module is controlled in temperature by a Peltier module formed by arranging a plurality of thermoelectric elements, between two insulating plates having a conductor circuit formed on one surface thereof, so as to be connected to the conductor circuits.